ABSTRACT
The outbreak of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a global threat to human health. Using a multidisciplinary approach, we identified and validated the hepatitis C virus (HCV) protease inhibitor simeprevir as an especially promising repurposable drug for treating COVID-19. Simeprevir potently reduces SARS-CoV-2 viral load by multiple orders of magnitude and synergizes with remdesivir in vitro. Mechanistically, we showed that simeprevir not only inhibits the main protease (Mpro) and unexpectedly the RNA-dependent RNA polymerase (RdRp) but also modulates host immune responses. Our results thus reveal the possible anti-SARS-CoV-2 mechanism of simeprevir and highlight the translational potential of optimizing simeprevir as a therapeutic agent for managing COVID-19 and future outbreaks of CoV.
ABSTRACT
cDNA coding a prolyl aminopeptidase (PAP) was cloned from Aspergillus oryzae and over expressed in Bacillus subtilis with a 6×His tag in N-terminus. The recombinant prolyl aminopeptidase was secreted to extracellular by adding 2 mM CaCl2 and 5% D-sorbitol in TB medium; the enzyme activity in fermented supernatant increased from 7.2 to 41.5 U mL-1. It has been purified 4.3-fold through Ni-chelating affinity chromatography with a recovery of 47.3%. The purified enzyme is stable below 50 °C and within pH 6-11, and with the highest activity at pH 7.5 and 50 °C. Several kinds of salt can activate enzyme activity in a certain concentration and the relative activity was 127.02% even when the concentration of NaCl reached 4.36 M. It cleaved N-terminal Pro residues from many peptides but shown different hydrolysis rates for various Pro-X dipeptides or peptides which are of different lengths. It combined with alkaline protease and leucine aminopeptidase to hydrolyze casein, many free amino acid especially proline and small peptide of hydrolysate increased significantly.
